The federal courts handle those who break federal laws while the state courts handle state laws. The differentiation is so that the judges can focus in on one section of crime instead of trying to focus on all of them. If they didn't judges would be overwhelmed and also there would be no separation in state and federal laws.

The advantages are that judges won't get influenced because they don't have to worry about re election. The disadvantage is that they can bring old ways of thinking that don't represent the country. I prefer the lifetime appointment because it doesn't cloud their judgment by making them worry about being re elected.

To make sure that the right people are handling the situation.